Why is struct tagName often different from typedef?

Question

Sometimes I see this code (I hope that I remember it correctly):

typedef struct st {
    int a; char b;
} *stp;

Whereas a regular template that I'm familiar with looks like this:

typedef struct st {
    int a; char b;
} st;

So what is the advantage in the first code example?

Answer 1

You probably mean this:

typedef struct ST {
  /* fields omitted */
} *STP;

An asterisk is at the end of the instruction. It simply means "define the STP type as a pointer to the structure of this type." The struct ( ST) tag is not needed, it is useful if you want to refer to the structure type again later.

You can also have both, for example:

typedef struct {
  /* fields omitted */
} ST, *STP;

This would allow us to use STfor designating the type of structure itself and STPfor pointers to ST.

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Answer 2

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Answer 3

, :

typedef struct{
   int a;
   char b;
} object, *objectPointer;

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objectPointer A = (objectPointer)malloc(sizeof(object));
A->a = 2;

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A->a = 2;

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Answer 4

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Answer 5

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